What Does the Idea of Multifactorial Causation in Drug Effects

What does the idea of multifactorial causation in drug effects suggest

A)  Each person will have the same physiological response to a drug, but there can be different psychological responses. 
B)  The effects of a drug depend on the dosage and the user's personal makeup and experience. 
C)  Taking several different drugs at the same time produces unpredictable effects. 
D)  Taking several different drugs at once increases their effectiveness.